tools: Add pid filter option (-p PID) for biotop & cachetop

man/man8/biotop.8

@@ -2,7 +2,7 @@
 .SH NAME
 biotop \- Block device (disk) I/O by process top.
 .SH SYNOPSIS
-.B biotop [\-h] [\-C] [\-r MAXROWS] [interval] [count]
+.B biotop [\-h] [\-C] [\-r MAXROWS] [\-p PID] [interval] [count]
 .SH DESCRIPTION
 This is top for disks. 
 
@@ -30,6 +30,9 @@ Don't clear the screen.
 \-r MAXROWS
 Maximum number of rows to print. Default is 20.
 .TP
+\-p PID
+Trace this PID only.
+.TP
 interval
 Interval between updates, seconds.
 .TP
@@ -98,7 +101,7 @@ Linux
 .SH STABILITY
 Unstable - in development.
 .SH AUTHOR
-Brendan Gregg
+Brendan Gregg, Rocky Xing
 .SH INSPIRATION
 top(1) by William LeFebvre
 .SH SEE ALSO

man/man8/cachetop.8

@@ -2,7 +2,7 @@
 .SH NAME
 cachetop \- Statistics for linux page cache hit/miss ratios per processes. Uses Linux eBPF/bcc.
 .SH SYNOPSIS
-.B cachetop
+.B cachetop [\-p PID]
 [interval]
 .SH DESCRIPTION
 This traces four kernel functions and prints per-processes summaries every
@@ -15,6 +15,10 @@ need updating to match any changes to these functions. Edit the script to
 customize which functions are traced.
 
 Since this uses BPF, only the root user can use this tool.
+.SH OPTIONS
+.TP
+\-p PID
+Trace this PID only.
 .SH KEYBINDINGS
 The following keybindings can be used to control the output of \fBcachetop\fR.
 .TP
@@ -86,6 +90,6 @@ Linux
 .SH STABILITY
 Unstable - in development.
 .SH AUTHOR
-Emmanuel Bretelle
+Emmanuel Bretelle, Rocky Xing
 .SH SEE ALSO
 cachestat (8)

tools/biotop.py

@@ -4,7 +4,7 @@
 # biotop block device (disk) I/O by process.
 # For Linux, uses BCC, eBPF.
 #
-# USAGE: biotop.py [-h] [-C] [-r MAXROWS] [interval] [count]
+# USAGE: biotop.py [-h] [-C] [-r MAXROWS] [-p PID] [interval] [count]
 #
 # This uses in-kernel eBPF maps to cache process details (PID and comm) by I/O
 # request, as well as a starting timestamp for calculating I/O latency.
@@ -13,6 +13,7 @@
 # Licensed under the Apache License, Version 2.0 (the "License")
 #
 # 06-Feb-2016 Brendan Gregg Created this.
+# 17-Mar-2022 Rocky Xing Added PID filter support.
 
 from __future__ import print_function
 from bcc import BPF
@@ -24,6 +25,7 @@
 examples = """examples:
  ./biotop # block device I/O top, 1 second refresh
  ./biotop -C # don't clear the screen
+ ./biotop -p 181 # only trace PID 181
  ./biotop 5 # 5 second summaries
  ./biotop 5 10 # 5 second summaries, 10 times only
 """
@@ -35,6 +37,8 @@
  help="don't clear the screen")
 parser.add_argument("-r", "--maxrows", default=20,
  help="maximum rows to print, default 20")
+parser.add_argument("-p", "--pid", type=int, metavar="PID",
+ help="trace this PID only")
 parser.add_argument("interval", nargs="?", default=1,
  help="output interval, in seconds")
 parser.add_argument("count", nargs="?", default=99999999,
@@ -92,9 +96,14 @@
 int trace_pid_start(struct pt_regs *ctx, struct request *req)
 {
  struct who_t who = {};
+ u32 pid;
 
  if (bpf_get_current_comm(&who.name, sizeof(who.name)) == 0) {
- who.pid = bpf_get_current_pid_tgid() >> 32;
+ pid = bpf_get_current_pid_tgid() >> 32;
+ if (FILTER_PID)
+ return 0;
+
+ who.pid = pid;
  whobyreq.update(&req, &who);
  }
 
@@ -124,6 +133,18 @@
  }
 
  struct who_t *whop;
+ u32 pid;
+
+ whop = whobyreq.lookup(&req);
+ pid = whop != 0 ? whop->pid : 0;
+ if (FILTER_PID) {
+ start.delete(&req);
+ if (whop != 0) {
+ whobyreq.delete(&req);
+ }
+ return 0;
+ }
+
  struct val_t *valp, zero = {};
  u64 delta_us = (bpf_ktime_get_ns() - startp->ts) / 1000;
 
@@ -146,7 +167,6 @@
  info.rwflag = !!((req->cmd_flags & REQ_OP_MASK) == REQ_OP_WRITE);
 #endif
 
- whop = whobyreq.lookup(&req);
  if (whop == 0) {
  // missed pid who, save stats as pid 0
  valp = counts.lookup_or_try_init(&info, &zero);
@@ -179,6 +199,11 @@
 else:
  bpf_text = bpf_text.replace('__RQ_DISK__', 'q->disk')
 
+if args.pid is not None:
+ bpf_text = bpf_text.replace('FILTER_PID', 'pid != %d' % args.pid)
+else:
+ bpf_text = bpf_text.replace('FILTER_PID', '0')
+
 b = BPF(text=bpf_text)
 if BPF.get_kprobe_functions(b'__blk_account_io_start'):
  b.attach_kprobe(event="__blk_account_io_start", fn_name="trace_pid_start")

tools/cachetop.py

@@ -11,6 +11,7 @@
 # Licensed under the Apache License, Version 2.0 (the "License")
 #
 # 13-Jul-2016 Emmanuel Bretelle first version
+# 17-Mar-2022 Rocky Xing Added PID filter support.
 
 from __future__ import absolute_import
 from __future__ import division
@@ -152,12 +153,15 @@ def handle_loop(stdscr, args):
  BPF_HASH(counts, struct key_t);
 
  int do_count(struct pt_regs *ctx) {
+ u32 pid = bpf_get_current_pid_tgid() >> 32;
+ if (FILTER_PID)
+ return 0;
+
  struct key_t key = {};
- u64 pid = bpf_get_current_pid_tgid();
  u32 uid = bpf_get_current_uid_gid();
 
  key.ip = PT_REGS_IP(ctx);
- key.pid = pid >> 32;
+ key.pid = pid;
  key.uid = uid;
  bpf_get_current_comm(&(key.comm), 16);
 
@@ -166,6 +170,12 @@ def handle_loop(stdscr, args):
  }
 
  """
+
+ if args.pid:
+ bpf_text = bpf_text.replace('FILTER_PID', 'pid != %d' % args.pid)
+ else:
+ bpf_text = bpf_text.replace('FILTER_PID', '0')
+
  b = BPF(text=bpf_text)
  b.attach_kprobe(event="add_to_page_cache_lru", fn_name="do_count")
  b.attach_kprobe(event="mark_page_accessed", fn_name="do_count")
@@ -251,9 +261,11 @@ def handle_loop(stdscr, args):
 
 def parse_arguments():
  parser = argparse.ArgumentParser(
- description='show Linux page cache hit/miss statistics including read '
+ description='Show Linux page cache hit/miss statistics including read '
  'and write hit % per processes in a UI like top.'
  )
+ parser.add_argument("-p", "--pid", type=int, metavar="PID",
+ help="trace this PID only")
  parser.add_argument(
  'interval', type=int, default=5, nargs='?',
  help='Interval between probes.'